In lithography techniques, for example, a resist film containing a resist material is formed on a substrate, and the resist film is subjected to selective exposure, followed by development, thereby forming a resist pattern having a predetermined shape on the resist film. A resist material in which the exposed portions of the resist film become soluble in a developing solution is called a positive-type, and a resist material in which the exposed portions become insoluble in a developing solution is called a negative-type.
In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have lead to rapid progress in the field of pattern miniaturization.
Typically, these miniaturization techniques involve shortening the wavelength (increasing the energy) of the exposure light source. Conventionally, ultraviolet radiation typified by g-line and i-line radiation has been used, but nowadays KrF excimer lasers and ArF excimer lasers are now starting to be introduced in mass production. Furthermore, research is also being conducted into lithography techniques that use an exposure light source having a shorter wavelength (higher energy) than these excimer lasers, such as extreme ultraviolet radiation (EUV), electron beam (EB), and X ray.
Resist materials for use with these types of exposure light sources require lithography properties such as a high resolution capable of reproducing patterns of minute dimensions, and a high level of sensitivity to these types of exposure light sources.
As a resist material that satisfies these conditions, a chemically amplified composition is conventionally used, which includes a base component that exhibits increased solubility in an alkali developing solution under the action of acid, and an acid generator component that generates acid upon exposure (for example, Patent Document 1).
In addition, a solvent developing process in which a developing solution containing an organic solvent (organic developing solution) is used instead of an alkali developing solution for a chemically amplified composition including similar components to those of the above chemically amplified composition is also known (for example, Patent Document 2).
In the case where the solvent developing process is employed, when the polarity of a base resin is increased, the solubility in the organic developing solution decreases relatively. As a result, the unexposed portions of the resist film are dissolved in the organic developing solution and removed, whereas the exposed portions remain as a pattern, resulting in the formation of a negative-type resist pattern. This type of solvent developing process that results in the formation of a negative-type resist pattern is also referred to as a negative tone development process.